Okay, I just understood that 'Prompt' was just a sort of view for 'Program'.
I'd like to make it very accessible, so please don't hesitate to report any difficulties with finding and understanding documentation and examples!
Then I think the name 'Prompt' may be misleading for those who doesn't know the MonadPrompt package. Maybe something like 'ProgramView' ?
What have we achieved? Both players still can only access functions from whatever monad m turns out to be. But now each strategy can pile its own custom monad stack on the Player m monad! And of course, the use of the m Monad is completely optional.
Of course, the custom monad stack has to provide a projection back to the Player m a type
runMyStackT :: MyStackT (Player m) a -> Player m a
game :: Monad m => Player m () -> Player m () -> m () As it is written, it requires both players to run in the SAME monad. And if have a network player ( e.g.* Player (StateT Handle IO)* ) and an AI storing former opponent's moves ( e.g. *(Monad m) => Player (StateT [Move] m)* ), then they can't be in the same monad...
According to what Bertram said, "each strategy can pile its own custom monad
stack ON the (Player m) monad".
Here, you are stacking the (Player m) monad ON the custom monad stack.
What is then the use of the 'm', in (Player *m*)? Is it not supposed to be a
custom monad? (MonadIO for human, Identity for AI, etc.)
But then, I don't see how the game function could work:
*
*
2010/4/14 Heinrich Apfelmus
Limestraël wrote:
I have some difficulties to see the use of PromptT, because in the tutorial, this type is never mentioned, and its operations (Return and :>>=) are instead constructors of ProgramT...
Would you have some concrete examples? Because there I'm a bit lost (since the tutorial doesn't match the operational package as it is, because of the type PromptT)...
The project page
http://projects.haskell.org/operational/
links to documentation that describes the differences to "The Operational Monad Tutorial", in particular the new Prompt and PromptT types. It also links to several examples. Two small examples are also included in the Haddock documentation.
I'd like to make it very accessible, so please don't hesitate to report any difficulties with finding and understanding documentation and examples!
Regards, Heinrich Apfelmus
-- http://apfelmus.nfshost.com
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